OK. Looks like a mechanical "acid" dip of a car body to reduce weight.

Nice job and 6 grams from one side is a good result. If you can get 4 from the other pin boss then anything else you shave will be heading to perfection.

__________________
1995 E300 Diesel

I'm gonna try and get a few more grams out of that side - no guts no glory. This metal removal is so tedious you have plenty of time to pluck up some extra courage!

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

That's funny because it's true.

It looks like some of the pin bosses are tapered and some are straight. It even looks like one piston has a straight side and a tapered side. Is that an illusion?

Out of curiousity, is the wide "casting line" on the bottom of the crown raised or lower than the rest of the surrounding area?

A faster tool for aluminum removal (as previously mentioned):


Smoothing up is important. Leave no sharp edges which could start a stress fracture.

__________________
When life gives you lemmings... make lemmingade.

The inside of the casting is actually quite uneven - the sides of the pin bosses are indeed at weird angles. The casting line is higher than the crown in the picture - it is space for the rings.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

no, he's talking about the parting line between the two halves of the piston between the pin bosses on the crown.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Oh right - that's lower

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I've been busy with other stuff recently so the problem isn't quite resolved yet.

The state of play at the moment is that I've got three pistons quite close in weight to each other - 469.4 (lightest as bought with out rings), 469.7 (modified 2nd lightest) and 471.9 (heaviest as bought).

The (new) heaviest piston that is awaiting the last bit of work is 488.2 grams

I'm going to try and get them all to be 469.X grams

(These weights are all without piston rings and pins fitted - so that's why there are different numbers from earlier on in the thread)

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Well at last after hours and hours of work I have four pistons with a difference in weight of one gram.

I'm not ever going to attempt this job with out a milling machine again!

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

How many hours? I'd have to say not many folks would have the patience to do this job!

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Many many more than I care to remember. It wouldn't surprise me if I had spent 20 hours on this job. Totally ridiculous - about half the time was spent using the wrong tools and working out which will work and which ones won't - a quarter of the time was spent flipping out and stressing out about "being careful".

It is a little bit like the first time you take out an engine - the second time goes quicker - and by the third time you can compete with the lads at the breakers yard...

...Today within three hours I lightened the last of the heavy pistons - that included a trip to the shop (took about 50 minutes) to go and buy yet another dremmel cutting tool.

I reckon I spent about 50 euros in dremmel cutting tools and those arse bucket little rolls of sand paper - next time milling machine - next time pay someone else to do it - it is a 30 minute job if that with the correct tools.

Perseverance - stubbornness - never surrender - give it some stick - bang your head against that brick wall!

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Glad you got it worked out though. I have ~2 hours into my lightweight vacuum pump plate. Once I got started I couldn't stop

__________________
$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

Have you got a link for your project?

(I guess you're on STD?)

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Stretch, it has been well worth doing what you did.

There is nothing worse than a doubt if you find the end result was to have a vibration. At least you know it wouldn't be caused by piston weight variation.

__________________
1995 E300 Diesel

Thanks for the vote of confidence - I hope I haven't cocked it all up and taken out too much strength. Still this is the only way to learn!

Here's my final configuration



I think I'll swap the combined set in cylinder 3 with cylinder 4 so that the heaviest is next to the flywheel.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!